Error 404 - page not found
 

Hello,
I'm a new user and having an issue running the vBulletin install script.

The manual says

"The Installer runs as a PHP script using your web browser. To start the installation process, open your browser and type the HTTP address of your forums directory, followed by /install/install.php, then hit the key or press the [Go] button to open the script."http://files.vbulletin.com/doc_image...taller_url.png


I'm typing;
http://www.mydomainname.com/forums/install/install.php
and getting error 404 - PAGE NOT FOUND


What have I done wrong?